Instruments, such as guitars and basses, have utilized passive pickups for over 60 years. Vintage guitars, such as the Fender Stratocaster™ guitar, Fender Telecaster™ guitar, and the Gibson Les Paul™ guitar, utilize passive pickups. Musicians, such as Jeff Beck, Eddie Van Halen, and Jimi Hendrix, utilized passive pickups to create a “classic” guitar sound that is well known to musicians as well as to the general public. Passive pickups are simple transducers built by wrapping many coils of copper wire around a permanent magnet, which is usually constructed of Alnico or ceramic. Pickups have a significant inductive component that results in the output impedance increasing with frequency. The location of the magnet in close proximity to the strings causes the strings to magnetize. Because of this, when the strings move, they disturb the magnetic field, and cause an electrical current to pass through the copper wire.
Today, many musicians prefer guitars with passive electronics and pickup systems. Passive electronics and pickup systems have a very high dynamic range. Thus, a musician can play a low amplitude whisper quiet part followed by a high amplitude part. Passive electronics and pickup systems tend to lose high-frequency detail and emphasize lower frequencies because the impedance varies with frequency. Thus, guitars with passive electronics and pickup systems produce a warm tone that is highly desired by many musicians. However, the frequency response rolls off even more when the instrument's volume control is set at less than maximum, thus most musicians are forced to never use the volume control except as an “effect” and generally leave the volume at maximum.
Some more recent instruments, such as the Alembic Series II guitar, utilize active electronics and pickup systems instead of passive electronics and pickup systems. An active electronics and pickup system is powered by an electrical power source, such as one or more batteries or an external power supply. Active electronics and pickup systems use coils of wire that are wrapped around a magnet, just like pickups in passive electronics and pickup systems. However, because voltage amplification is provided by the active circuit, the pickups typically use fewer turns on the coil.
The pickups in an active electronics and pickup system are typically coupled to a preamplifier that is built into the guitar. Thus, the output signal impedance of guitars with active electronics and pickup systems is constant with respect to frequency and is much lower than passive electronics and pickup systems. As a result, such guitars have enhanced clarity and sonic detail, when compared with guitars that utilize passive electronics and pickup systems. Thus, today many musicians prefer guitars with active pickups because such pickups enable sounds that have a tight and focused clarity, and permit the instrument volume control to be set at less than maximum for the desired output level without compromising the frequency response.
As discussed above, the impedance of the output signal of guitars with passive electronics and pickup systems varies with respect to frequency. In addition, the response of the output signal of such guitars can be degraded by interfacing the guitar to a guitar amplifier, an effect box (also known as a pedal and as a stomp box), or a mixer. In particular, the load capacitance of a guitar cord, which interfaces the guitar to an audio-receiving device, such as a guitar amplifier, an effect box, or a mixer, as well as the load of the audio-receiving device, can degrade the high frequency response of the guitar.
Alembic, Inc. (“Alembic”) has long known of the effect of guitar cable load capacitance on the response of guitars with passive electronics and pickup systems. As a result, beginning in 1971, Alembic designed and marketed a “Blaster” aftermarket preamplifier for installation inside an existing guitar equipped with a passive electronics and pickup system. Later, Alembic, Inc. designed and marketed a “Super Cord Active Cable”. A schematic diagram of the Alembic Super Cord Active Cable is shown in FIG. 1.
As shown in FIG. 1, the Super Cord Active Cable included an instrument plug. The instrument plug included a conventional first ¼ inch diameter plug with a tip, a sleeve, a tip terminal, a sleeve terminal, and a housing. The instrument plug was intended to be inserted into the well-known conventional ¼ inch jack of guitars with passive electronics and pickup systems. The instrument plug's tip received the output signal from the guitar. Similarly, the instrument plug's sleeve was coupled to the guitar's ground.
The instrument plug of FIG. 1 also housed a preamplifier circuit. The preamplifier circuit included two resistors and a N-channel field effect transistor (“FET”). As shown in FIG. 1, the gate of the FET was coupled to the tip terminal and to the first terminal of a 1 MΩ, resistor, the second terminal of which was coupled to ground. The source of the N-channel FET was coupled to the first terminal of a 13 kΩ resistor, the second terminal of which was coupled to ground. The tip terminal, the sleeve terminal, the 1 MΩ resistor, the 13 kΩ resistor, and the N-channel FET were all located within the conventional housing (not shown) of the first ¼ inch diameter plug. An example of such a conventional housing is shown as item number 30 of FIG. 3 of U.S. Pat. No. 5,585,767 to Wright.
As shown in FIG. 1, the Super Cord Active Cable also included a first cable that included two conductors. The length of the first cable was approximately 19 feet. The first end of the first cable was coupled to the instrument plug. Specifically, the first conductor of the first cable was coupled to the drain of the instrument plug's N-channel FET. The second conductor of the first cable was coupled to the instrument plug's ground. The second end of the first cable was coupled to a battery box.
As shown in FIG. 1, the battery box included a 9-volt battery that included a positive terminal and a negative terminal. The positive terminal of the 9-volt battery was coupled to the first terminal of a 22 kΩ resistor, the second terminal of which was coupled to the first conductor of the first cable. The negative terminal of the 9-volt battery was coupled to the second conductor of the first cable.
As shown in FIG. 1, the Super Cord Active Cable also included a second cable with two conductors. The first end of the second cable was coupled to the battery box. Specifically, first conductor of the second cable was coupled to the battery box's 22 kΩ resistor as shown in FIG. 1. The second conductor of the second cable was coupled to the negative terminal of the battery box's 9-volt battery.
While FIG. 1 shows that the length of the first and second cables are the same, the length of the first cable was approximately 19 feet and the length of the second cable was approximately 1 foot. These cables were flexible and allowed the musician to move freely with respect to an audio-receiving device, such as the musician's amplifier, effect box, or mixer.
As shown in FIG. 1, the second cable was coupled to an amplifier plug. The amplifier plug included a 1 μF capacitor, a 174 kΩ resistor, and a conventional second ¼ inch diameter plug with a tip, a sleeve, a tip terminal, a sleeve terminal, and a housing. The first terminal of the 1 μF capacitor was coupled to the first conductor of the second cable. As shown in FIG. 1, the second terminal of the 1 μF capacitor was coupled to both first terminal of the 174 kΩ resistor and to the tip terminal of the second ¼ inch diameter plug. The second conductor of the second cable was coupled to the second terminal of the 174 kΩ resistor as well as to ground. Finally, the sleeve terminal of the second ¼ inch diameter plug was coupled to ground. The 1 μF capacitor and the 174 kΩ resistor were located within the conventional housing (not shown) of the second conventional ¼ inch diameter plug. The amplifier plug was intended to be coupled to an amplifier, an effect box, or a mixer.
As is evident from FIG. 1, the Super Cord Active Cable of FIG. 1 included a voltage amplifier that transferred a voltage from an instrument, having a high output impedance level, to a flexible cable with a lower output impedance level. Thus, the Super Cord Active Cable voltage-buffered the output signal of an instrument's passive pickups from the capacitive load of the first cable and the second cable, as well as the loading of an audio-receiving device, such as an amplifier, effect box, or mixer. As a result, vintage guitars with passive electronics and pickup systems that were interfaced with amplifiers, effect boxes, or mixers, via the Super Cord Active Cable had enhanced clarity and sonic detail when compared to interfacing the guitars to such devices via conventional guitar cords.
While the Super Cord Active Cable provided enhanced clarity and sonic detail to vintage guitars, the Super Cord Active Cable limited the ability of musicians to authentically reproduce certain classic sounds. Thus, a need exists for an interconnect system that provides the enhanced clarity and sonic detail of the Super Cord Active Cable and that enables musicians to authentically reproduce classic sounds for which vintage instruments were well known.
While the gain of the Super Cord Active Cable is optimal for certain instruments, it is not optimal for some instruments. Thus, a need exists for an interconnect system that enables a musician to have access to the enhanced clarity and sonic detail of the Super Cord Active Cable and that provides the musician with the ability to set the gain of the interconnect system's preamplifier.
As discussed above, the Super Cord Active Cable provided a significant increase in clarity and sonic detail. However, in some circumstances the frequency response of the Super Cord Active Cable is not optimal. Thus, a need exists for an interconnect system that enables a musician to have access to the enhanced clarity and sonic detail of the Super Cord Active Cable and that provides the musician with the ability to modify the frequency response of the interconnect system's output signal.